1999 Sep 28 2
Philips Semiconductors Product specification
Octal bus transceiver; 3-state 74AHC245; 74AHCT245
FEATURES
• ESD protection:
HBM EIA/JESD22-A114-A
exceeds 2000 V
MM EIA/JESD22-A115-A
exceeds 200 V
CDM EIA/JESD22-C101
exceeds 1000 V
• Balanced propagation delays
• All inputs have a Schmitt-trigger
action
• Inputs accepts voltages higher than
V
CC
• For AHC only:
operates with CMOS input levels
• For AHCT only:
operates with TTL input levels
• Specified from
−40 to +85 and +125 °C.
DESCRIPTION
The 74AHC/AHCT245 is a
high-speed Si-gate CMOS device.
The 74AHC/AHCT245 is an octal
transceiver featuring non-inverting
3-state bus compatible outputs in
both send and receive directions.
The74AHC245/74AHCT245features
an Output Enable (OE) input for easy
cascading and a send/receive (DIR)
input for direction control.
OE controls the outputs so that the
buses are effectively isolated.
FUNCTION TABLE
See Note 1.
Note
1. H = HIGH voltage level;
L = LOW voltage level;
X = don’t care;
Z = high-impedance OFF-state.
QUICK REFERENCE DATA
GND = 0 V; T
amb
=25°C; t
r
=t
f
≤3.0 ns.
Notes
1. C
PD
is used to determine the dynamic power dissipation (P
D
in µW).
P
D
=C
PD
× V
CC
2
× f
i
+ ∑ (C
L
× V
CC
2
× f
o
) where:
f
i
= input frequency in MHz;
f
o
= output frequency in MHz;
∑ (C
L
× V
CC
2
× f
o
) = sum of outputs;
C
L
= output load capacitance in pF;
V
CC
= supply voltage in Volts.
2. The condition is V
I
= GND to V
CC
.
INPUTS INPUTS/OUTPUTS
OE DIR A
n
B
n
L L A = B inputs
L H inputs B = A
HXZZ
SYMBOL PARAMETER CONDITIONS
TYPICAL
UNIT
AHC AHCT
t
PHL
/t
PLH
propagation delay C
L
=15pF;
V
CC
=5V
3.5 5.0 ns
A
n
to B
n
, B
n
to A
n
C
I
input capacitance V
I
=V
CC
or GND 3.5 3.5 pF
C
O
output
capacitance
4.0 4.0 pF
C
PD
power dissipation
capacitance
C
L
=50pF;
f = 1 MHz;
notes 1 and 2
12 15 pF
